A budget is requested for acquisition of a benchtop instrument for matrix assisted laser desorption mass spectrometry to provide rapid determinations of molecular weights in conjunction with studies of protein processing, modification and structure-function relations. The use of membranes will be developed as surfaces for matrix assisted laser desorption, including desorption of the products of protease digestion and chemical reactions carried out directly on the membrane. Collaborative studies of modified oligonucleotides, of polysaccharides and of noncovalent protein complexes will include methods development in those areas. It is intended that this installation will operate part of the time in a walk-up, multi-user mode, allowing molecular biologists and biochemists to make their own molecular weight determinations. Training and proof of method will precede most of these applications.